In the discussion of the background that follows, reference is made to certain structures and/or methods. However, the following references should not be construed as an admission that these structures and/or methods constitute prior art. Applicant expressly reserves the right to demonstrate that such structures and/or methods do not qualify as prior art.
Generally, metal removal rates are a function of feed rate and the number of teeth that the cutting tool is capable of incorporating within a given diameter of the tool or other available space on the tool. Generally, longevity of tool life is a function of the number of cutting edges participating in the material removal process. The more cutting edges that are on the tool, the more prolonged the tool life will proportionally be. In addition to increasing tool life and material removal rate, a plurality of cutting edges contributes to reducing the time for cut interruption. This makes cutting smoother and the quality of the surface better. A smoother cut, also, means less wear of machinery.
There are known methods to achieve high density of cutting edges. U.S. Pat. No. 889,829 shows a traditional tool utilizing a solid grinding technique to produce a high density of teeth. It is a simple method. However, regrinding of the tool is expensive and, as a result, the cutter loses its original size. Also, the compatibility of this method with modern cutting materials like carbide, ceramic, PCD and CBN is very unlikely, due to the high cost.
The problems with the traditional tools, such as in U.S. Pat. No. 888,829, was resolved by utilizing indexable cutting inserts with two cutting edges, such as disclosed in U.S. Pat. No. 5,209,611. An example of such a cutting insert is shown in FIG. 1. The cutting insert 2 has two cutting edges 4,6 that are active at each index position of the cutting insert 2. A benefit of this design is an increase in the number of cutting edges in combination with recyclable inserts. This allows using one cutter body with multiple inserts. The cutting insert 2 is located in a cutter body (not shown) in relation to walls 8,10, which generally act as locating surfaces.
Also, there is a very high manufacturing expense of this type of cutter body. Typically, in order to position both cutting edges 4,6, accurately on the same cutting diameter, pockets for the cutting insert 2 in the tool body have to be machined extremely precise. Milling of pockets is made with solid end mills of small diameters, which usually deflect due to the unfavorable ratio between length and diameter. As a result, to increase precision of milling cutters utilizing the cutting insert 2 of FIG. 1, the seating pockets are jig ground, which substantially increase the cost of the body.